-LRB- CNN -RRB- -- In the last decade of the 20th century , the Turkish lira fell in value 1,000 times against the U.S. dollar , meaning that tourists returning to that country after several years found that any old money they still possessed since their last visit had become almost worthless .

Now as fears grow about whether Greece will stay in the euro , and the possible domino effect this could cause , many prospective holidaymakers appear to be having second thoughts about visiting that country and other economically troubled members of the 17-nation eurozone , such as Spain or Portugal .

And while tourists may be bulking up their cash reserves in the case of a euro exit , others may be concerned about safety if violent street protests resume against austerity cuts .

What is the financial situation now ?

Political deadlock is leading to fears that Greece will not have a government in place when it needs to make critical debt payments , which could in turn jeopardize its place in the eurozone .

On Monday , Greeks withdrew up to $ 800 million from Greek banks , and the threat of a banking panic heightened concern of a default . Fears of contagion spilled over into bond markets in Spain and Italy .

The idea that has investors around the globe worried is the so-called `` Grexit '' -- or Greek exit from the eurozone -- a tricky scenario that is now looking like a real possibility .

English bookmakers Ladbrokes stopped taking bets after gamblers lined up to put money on it last week . Other betting companies are giving odds on Greece leaving the euro as low as 1/10 , while the odds on Spain leaving are about 6/1 .

What effect is uncertainty having on tourism within the eurozone ?

Many in the travel industry admit bookings to Greece are lower than in previous years , with other countries benefiting .

Hotel reservations on popular holiday destinations such as Corfu and Crete are down by up to 50 % compared to the same period before last month 's indecisive election , according to the Hellenic Hotel Federation .

Sean Tipton of the Association of British Travel Agents blames some inaccurate coverage of concerns about Greece 's financial problems as a factor . `` This is having a positive effect on Spanish travel , for example , with bookings higher than normal , '' he told CNN .

`` Travelers are advised to take spending money in cash , as in the event of Greece leaving the euro there may be questions about whether you could still pay by credit or debit cards . ''

Despite tourism contributing about $ 10,5 billion , or about 16 % of Greece 's gross domestic product , officials brushed off concerns . `` There was also a financial crisis in Greece last year as well and we had a record year with a 10 % increase in the number of visitors , '' said Konstantinos Zikos , president of the Greek National Tourism Organization .

`` Because of the crisis , early booking are down around Europe at the moment . However , Greece is a beautiful and safe country so we are optimistic that tourism wo n't be strongly affected . ''

In the longer term , if Greece does leave the euro , it could mean it becomes a much cheaper country to visit , as Britain 's biggest travel company Thomas Cook pointed out . `` We believe there are positives and negatives for the travel industry in the event that Greece were to leave the euro , '' the firm said .

Should tourists be worried about buying euros for foreign travel ?

On the face of it , tourists have n't had it so good for a long time : The euro is at a three-year low against the British pound and is as weak against the U.S. dollar as it has been since 2010 . This should mean the cost of hotels and restaurants is lower than it has been for a few years .

Travel experts say that whatever happens with Greece and the euro this summer , tourists visiting economically troubled European countries , such as Greece , Italy , Spain and Portugal -- all major tourist destinations -- are unlikely to lose out .

If Greek does leave the euro this could lead to contagion , and other countries joining them , but few analysts believe the whole euro project is likely to collapse in the next year or so . In other words , it 's safe to buy euros , but keep an eye on the exchange rate , which is continuing to strengthen in favor of world currencies .

How can travelers ensure they do n't lose out ?

Travel writer Simon Calder said he planned to visit Greece this summer , and was taking two precautions .

`` The first was to add an extra $ 100 to my estimated spending , '' Calder wrote on his blog . `` Normally I rely on plastic for emergencies , but were Greece to leave the euro , electronic banking could freeze for up to a week and prevent debit and credit card transactions .

`` Next , I insisted on $ 5 , $ 10 and $ 20 notes . If Greece leaves the euro , the most likely interim currency is the existing euro overprinted with a Greek delta symbol -LRB- for `` drachma '' -RRB- , or possibly with a corner clipped .

`` The value of the Greek euro would fall by perhaps 40 per cent . While traders sort themselves out , and before a market in the Greek currency begins , tourists are likely to pay in euros but be given change in new money . Pay for a $ 15 round of drinks with a $ 50 note , and you could get back change in Greek currency worth only $ 20 . That is why low-denomination notes are so useful . ''

Do street protests against austerity cuts mean Greece or another country is unsafe ?

No . There have been occasional protests in big cities , such as Athens and Thessaloniki , but most say Greece remains safe . Posts on online forums were scathing about what they said was the media blowing the unrest out of proportion , although there are some warnings that strikes could disrupt travel into and around the country .

ABTA 's Sean Tipton said `` There 's an element of concern about personal safety with sporadic unrest in Athens , but most places where tourists visit are safe .

`` In reality this is one of the best times to visit Greece , as prices should come down , thanks to supply and demand . ''

UK travel firm Thomas Cook said it was `` closely monitoring the evolving situation in Athens . Most of our holidaymakers are on the country 's islands where you 'd never know anything was going on . ''

@highlight

Some holidaymakers appear to be having second thoughts about visiting Greece

@highlight

Others concerned about safety if violent street protests resume against austerity cuts

@highlight

Idea that has investors worried is the so-called `` Grexit '' -- or Greek exit from the eurozone

@highlight

Travel experts say tourists visiting economically troubled countries unlikely to lose out